Electronics, Lighting, & Gadgets - Dynamo lighting with dual headlights and a taillight

I have what's probably a stupid question for most of y'all in this forum -- I'm pretty new to dynamo lightng and currently have the following light setup on my '73 Gitane TdF:

Shimano DH-3D71 dynamo hub
B&M Lumotec Round (switched primary w/ 2.4 W bulb)
Schmidt E6Z (secondary w/ 3.0 W bulb)
B&M 4D Lite Plus (LED Taillight .6 W)

The primary and secondary headlights (wired using Peter White's instructions) are both normally very bright and working correctly, with the primary at full brightness at about 4 mph, and the seconday at full brightness at about 12 mph. When the tail light is connected to the primary headlight's spade connector, the primary gets significantly dimmer and won't come up to full brightness, but the tail light and secondary do achieve full brightness.

Is it common for the primary to dim significantly when using a wired tail light, or is it likely my primary light has a bad mechanical connection somewhere (say in the switch, etc)? I'd like to move the primary back to my commuter and pick up either an E6 primary or a Lumotec primary (with a standlight) for the Gitane, and am wondering if the taillight will produce the same results on another primary headlight.

FWIW, my Gitane is used as a combination rain bike/night bike...used on a combination of unlit MUP's, country roads, and lit urban streets.

Thanks in advance,

Ron Banks
Fort Worth, TX

sounds like those connections put the taillight in parallel with the headlight. I'm thinking it should be in series.

Sorry to take so long to get back on this...

Unterhausen, thanks for your thoughts on my lighting problem...I've since tried running the taillight in paralell and in series (and changing the polarity, etc). While the headlights are in series, adding the taillight to the series unfortunately didn't work any better.

FWIW, I've since changed from a primary lumotec round to an E6, and am running the tailight off the taillight port on the primary headlight. With the Schmidt (E6)+ taillight, the primary dims by about 10% (rough estimate) when the taillight is connected. It's much better than with the old primary headlight, but I'll try it a bit longer before I decide to stick with the wired taillight or not.

Thanks again for your help!

lutemake3: I run a SON dyno hub and twin B & M IQ Flys in series, plus a B & M 4D Toplite wired taillight. I'm pretty pleased with the light output of the LED headlights, and I think you would be too. According to Peter White, the IQ Fly is as bright as an E6, but with a much wider beam. Next time you look for headlights, consider the LED IQ Fly.--george

PS I run both IQ Flys as "daytime running lgiths" on all the time.